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#1
12-12-02, 07:07 PM
rmunk
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My main panel is rated at 100 amps and I'm going to add a subpanel so I can add one more circuit. The main now has a double 20amp brker, single 20amp brker, & a 30amp brker. Want to add a 60amp sub-panel, move the 30 amp brker to the sub plus add a 20 amp to the sub. Then put a 60 amp double pole breaker in the main to feed the sub. End results: main-60amp brker, single 20amp brker and a double 20amp brker. Sub-30 amp brker and a 20 amp brker. My calculated total draw is 65 amps. Is my thinking ok?

The main being rated at 100amps- does that mean can not exceed a total of 100 amp with breakers or a total draw of amps?

#2
12-12-02, 07:17 PM
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Join Date: Dec 2001
Location: New York
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The excersise of adding breaker values does not have value. You need to determine the actual demand of the circuits and their usages. If you are concerned about oveloading the main panel, perform a demand load calculation.
http://www.homewiringandmore.com/hom...DmdCalc02.html
The main breaker in the main panel will limit you to 100 amps of non-continuous load on each of the incomming hot phases.

#3
12-12-02, 09:05 PM
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You said, "My calculated total draw is 65 amps. Is my thinking ok?" Tell us how you computed th 65 amps and we'll tell you if your thinking is okay.

#4
12-12-02, 09:58 PM
rmunk
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Did the following: total sq ft x 3w = 4527 plus 3 small app circuits = 4500 total = 9027

Then fridge = 1560w heater = 1500w dryer = 6500w mircowave = 900w 4 outdoor receptcals x 180 = 720 for total of 20,207w - 10,000w gross load = 10,207 x.40 = 5104 = 10,000 = 15,104 then divided by 230 = 66 amps

got from black and decker electrical book

#5
12-12-02, 10:11 PM
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All gas cooking, gas heat, gas water heater, no air conditioning, no pool? Say yes to all that and you're good. Nice job!

#6
12-12-02, 11:47 PM
rmunk
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That is a yes! Thanks!

#7
12-13-02, 08:45 AM
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I bet your figure would be even lower if you took that 6500 watt microwave out and replaced it with a 650 one.

#8
12-13-02, 11:06 AM
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sberry, you parsed it wrong. Look again.

#9
12-13-02, 12:40 PM
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Do you have a Service panel with a 2-pole 100 amp circuit-breaker as the Service Dis-connect or a "Main Lugs" panel rated at 100 amps that will accomodate three 2-pole breakers?

#10
12-13-02, 09:31 PM
rmunk
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The service disconnect breaker is a 60 amp.

#11
12-14-02, 08:53 AM
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Trying to get 65 amps out of a 60-amp service isn't going to work. Sounds like you need an upgrade.

#12
12-14-02, 08:57 AM
rmunk
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My main panel is rated for 100amp and the disconnect main service breaker is 60amps. My total draw for the house is 66 amps (see "? about sub-panel" post) is this ok?

#13
12-14-02, 09:00 AM
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No. You need a service upgrade. Start by contacting your power company. They will need to check to see if they need to upgrade their stuff. Then you'll likely need to update the wire from your meter to your panel,

#14
12-14-02, 09:12 AM
rmunk
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The main panel itself is rated 100amps, so should I upgrade to a 100amp main breaker only or upgrade the panel too? I do not see adding any more circuits in the future.

Can I do the upgrade myself?

#15
12-16-02, 10:01 AM
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"Can I do the up-grade myself?"-----Only the local inspectors in your municapality can answer your question.In my area Con Edison won't even un-lock a meter until they receive a "request" form with a licence # attached.----Good Luck!!!